A variety of hand-held, manually operated mechanical apparatus are known for selectively dispensing thick, yet flowable semisolid or viscous liquid materials such as gels, pastes, sealants, adhesives, lubricants and caulking materials. Many of these "dispenser gun" apparatus replaceably receive an elongate dispenser tube or cartridge filled with the semisolid or viscous liquid material to be dispensed. The dispenser cartridge typically has a nozzle at its leading end and a piston slidably and substantially sealingly received in its rearward end. Dispenser guns of this sort usually include a handle having a pivotally mounted trigger which may be squeezed by the user to activate piston advancing means. Typical piston advancing means may comprise an elongate rod incrementally advanceable by a pawl and ratchet mechanism linking the rod and the trigger. The forward end of the rod is adapted for contact with the dispenser cartridge piston and incrementally propels the piston as the user squeezes and releases the trigger. As the piston is advanced, semisolid or viscous liquid is discharged from the dispenser tube.
Representative examples of such apparatus include conventional caulk dispensing guns and the Bate Mate.TM. gel or paste pest bait material dispenser gun marketed by Syrvet, Inc. of Waukee, Iowa. These apparatus include notched or grooved piston advancement rods which are incrementally moved forwardly with each squeeze and release of their triggers. Because their advancement rods can only move forwardly, except when they are deactivated for replacing a spent cartridge with a new cartridge, these apparatus apply continuous pressure against the cartridge piston. Consequently, undesirably "post-extrusion" of excess quantities of semisolid or viscous liquid may occur through the cartridge nozzle following a squeeze and release cycle of the trigger. When using such apparatus considerable care must be exercised to assure that the material being dispensed is neither wasted through post-extrusion nor applied in amounts greater or less than necessary to achieve the intended application objectives.
U.S. Pat. No. 5,022,563 discloses a hand-held dispenser gun which addresses the problem of post-extrusion often encountered when dispensing semisolid or viscous liquid materials. The dispenser gun described therein includes a drive plunger element in the form of an elongate rod for advancing the semisolid or viscous fluid material cartridge piston. The plunger rod has threads, notches or grooves along its length which are adapted for engagement by a spring biased pawl operatively driven by a spring biased, squeezable trigger. In operation, the user squeezes the trigger to advance the plunger rod from a first "at rest" position out of contact with the cartridge piston to a second position where the plunger rod contacts and advances the cartridge piston to dispense a quantity of material from the nozzle of the cartridge. Upon release of the trigger, the gun is designed such that the plunger rod becomes automatically disengaged from the cartridge piston and returns to the first position, thereby relieving the cartridge of pressure that might cause post-extrusion of material from the nozzle.
The pressure relief capability of the dispenser disclosed in U.S. Pat. No. 5,022,563 is useful for meting out controllable quantities of viscous fluid material from the dispenser cartridge. However, the dispenser gun is somewhat cumbersome to use. Specifically, the plunger rod must be manually advanced by physically pushing the rod forwardly in a motion separate from squeezing and releasing the trigger each time the user desires to dispense additional material from the cartridge. In confined, difficult to reach areas, operation of such a gun would be especially onerous.
Additionally, presently existing semisolid and viscous liquid material dispenser guns are capable of dispensing only such materials. In certain situations it would be beneficial for a single dispenser gun to have the capability to dispense not only semisolids and viscous liquids but materials of other physical consistencies such as, for example, powdered, granular or other particulate materials. For instance, pest control professionals often need to dispense semisolid or viscous liquid pest baits and/or granular baits at the same extermination site. Heretofore, these workers have been required to possess an inventory of equipment including at least one apparatus for hand-dispensing semisolid or viscous liquid baits and another for dispensing particulate baits.
An advantage exists, therefore, for a hand-held dispenser which is capable of dispensing semisolid, viscous liquid and particulate materials.
A further advantage exists for a hand-held dispenser which, when dispensing semisolids and viscous liquids, precisely dispenses such material without wasteful post-extrusion by simply squeezing and releasing a trigger movably mounted to the dispenser.
Further advantages exist for an adaptor for mounting a particulate materials dispenser cartridge to a hand-held dispenser as well as particulate material dispenser cartridges suitable for mounting to such a dispenser.